The present invention relates generally to an electrophotographic image forming apparatus, such as a copying machine or a printer, and, more specifically, to a multicolor image forming apparatus having a plurality of developing units respectively using different color toners, and capable of forming two-color images.
An image forming apparatus having a plurality of developing units respectively using different color toners and removably arranged around an electrostatic latent image carrying member has been put to practical use. This image forming apparatus, however, simply forms a single-color image by selectively operating one of the plurality of developing units.
In U.S. patent application Ser. No. 120,595 (Filed on Nov. 13, 1987), the inventors of the present invention have proposed a two-color image forming apparatus capable of forming two-color images by operating two developing units in a timed relation. The two developing units of this two-color image forming apparatus need to be disposed respectively at predetermined positions. Otherwise the two-color image forming apparatus is unable to form a desired two-color image even when a two-color image forming mode is selected.